[WIP] DCOS_OSS-3960 - Accept a host param in IAM methods

[mrnugget]

High-level description

Changes the IAM methods to accept an optional host parameter

Corresponding DC/OS tickets (obligatory)

These JIRA ticket(s) must be updated (ideally closed) in the moment this PR lands:

• [DCOS_OSS-3960] DC/OS Test Utils - Take a "host" parameter for Iam methods - JIRA

Related tickets (optional)

Other tickets related to this change:

Related dcos-launch and dcos PRs

Is this change going to be propagated up into another repo? Test the change by bumping the dcos-test-utils SHA to point to these changes to test it. Link the corresponding PRs here:

Checklist for all PRs

• Included a test which will fail if code is reverted but test is not. If there is no test please explain here:
• Include a test in dcos-integration-tests in https://github.com/dcos/dcos or explain why this is not applicable:
• Include a test in https://github.com/dcos/dcos-launch or explain why this is not applicable:

Integration tests were run and

• Integration Test - Enterprise (link to job: )
• Integration Test - Open (link to job: )

PLEASE FILL IN THE TEMPLATE ABOVE / DO NOT REMOVE ANY SECTIONS ABOVE THIS LINE

Instructions and review process

What is the review process and when will my changes land?

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Reviewers should be:

• Developers who understand the code being modified.
• Developers responsible for code that interacts with or depends on the code being modified.

It is best to proactively ask for 2 reviews by @mentioning the candidate reviewers in the PR comments area. The responsibility is on the developer submitting the PR to follow-up with reviewers and make sure a PR is reviewed in a timely manner.

[cgawron1]

@orsenthil @cprovencher take a look